Jenkins

What is Jenkins?

Jenkins is the long-established open-source automation server for building CI/CD pipelines. It builds, tests, and deploys software by running jobs (increasingly defined as code in a Jenkinsfile), and it’s extended through an enormous ecosystem of plugins (thousands of them) that integrate with virtually every tool, language, and platform. For over a decade Jenkins was the dominant CI/CD tool, self-hosted on your own infrastructure, and it still runs a vast amount of the world’s pipelines — but it now competes against a generation of lighter, git-native alternatives that have eroded its lead.

Its strength and its weakness are the same thing: plugins and self-hosting

Jenkins’s defining trait is flexibility through plugins — if you need to integrate with something, there’s almost certainly a plugin, and you can automate nearly anything. Combined with self-hosting (full control over the environment, runs anywhere, keeps everything in-house — valuable for strict security/compliance or air-gapped environments), this made Jenkins enormously capable. But the same traits are its liabilities. The plugin ecosystem is a double-edged sword: plugins vary in quality and maintenance, create dependency and version-compatibility headaches, and are a recurring security concern (vulnerable or abandoned plugins are a real attack surface, and Jenkins security advisories frequently center on plugins). Self-hosting means operational burden: you install, scale, secure, upgrade, and maintain the Jenkins controller and its agents yourself — versus modern SaaS CI where the provider handles all of that. Pipelines are configured with a Groovy-based Jenkinsfile that’s powerful but has a steeper learning curve than the clean YAML of newer tools.

The honest modern positioning

The fair assessment in 2026: Jenkins is mature, battle-tested, and maximally flexible, but showing its age, and it’s losing ground to GitHub Actions, GitLab CI, CircleCI, and cloud-native pipelines. Those newer tools are git-native (tightly integrated with the repository and pull-request workflow), use simpler YAML configuration, and are often managed (no server to run), which removes exactly the operational and security toil Jenkins imposes. The decision comes down to tradeoffs: choose Jenkins when you need its unmatched flexibility, extensive plugin integrations for a complex/heterogeneous toolchain, self-hosting for strict control or air-gapped/compliance reasons, or you have a large existing Jenkins investment; lean toward modern alternatives for new projects wanting low operational overhead, clean configuration, and tight git integration — which is most greenfield cases. The recurring mistakes are Jenkins-flavored versions of general CI/CD pitfalls plus its own: neglecting plugin security and updates (the top Jenkins-specific risk), letting the controller become an under-maintained single point of failure, hardcoding secrets instead of using the credentials store, and slow un-optimized pipelines. Many teams keep Jenkins where it’s entrenched while defaulting new work to lighter tools.

What people get wrong

• Neglecting plugin security — vulnerable, abandoned, or excessive plugins are Jenkins’s number-one risk; keep them minimal, updated, and audited.
• Underestimating operational burden: self-hosting means you own scaling, upgrades, and hardening — newer managed CI removes this, which matters for new projects.
• Choosing it reflexively for greenfield — for new work, git-native YAML tools (GitHub Actions, GitLab CI) are usually simpler; reserve Jenkins for cases its flexibility or self-hosting genuinely requires.

Primary source: Jenkins documentation